Apparatus for liquid removal



Dec. 12, 1967 A. R. HAMILTON 3,357,345

APPARATUS FOR LIQUID REMOVAL Filed Feb. 2, 1965 3 Sheets-Sheet l Dec.12, 1967 Q A. R. HAMILTON APPARATUS FOR LIQUID REMOVAL 3 Sheets-Sheet 2Filed Feb. 1965 Dec. 12, 1967 A. R. HAMILTON 3,

APPARATUS FOR LIQUID REMOVAL Filed Feb. 1965 3 Sheets-Sheet 5 UnitedStates Patent 3,357,345 APPARATUS FOR LIQUID REMOVAL Alan R. Hamilton,Paxton, Mass, assignor to Rice Barton Corporation, Worcester, Mass, acorporation of Massachusetts Filed Feb. 2, 1965, Ser. No. 429,755 11Claims. (Cl. 100-158) ABSTRACT OF THE DISCLOSURE A screw filter coupledthrough a closed circuit to a disc press input zone, with a pressuresensor in the input zone to vary the disc speed to keep input pressureconstant. Other features include labyrinth disc seals, a doctorincorporating a wash water chamber and a knot removing auger, and ashredder.

This invention relates to apparatus for reducing the liquid content of amixture of liquid and solid material.

It is a primary object of the invention to provide such apparatus whichcombines simplicity of operation and maintenance with flexibility andhigh throughput capability. It is a further important object to provideenclosed two-stage combination apparatus for successively removingliquids in large quantity in screw filter and disc press stages. Afurther significant object is provision of such a screw filter compactin size and yet operable at increased pressures and rates of throughput,and with reduced loss of fines. Another important object is provision ofsuch a disc press in which bearing requirements are simplified andproduction of knots is minimized. Another important object is provisionof such a disc press capable of operating efliciently during fluctuationof rate of input. Other important objects are provision in a disc pressfor operating on thinner slurries, for removal of knots that do form,and for washing out without shutdown. Another important object is toprovide for ejection from a disc press of damp solids shredded foreflicient pneumatic conveying.

The invention features in its combination aspect an enclosed system inwhich a screw filter discharges directly into a disc press. In preferredembodiments of the screw filter subcombination, there are featured axesof symmetry in which that of one or both extremities is at an angle tothat of the center portion, eliminating blind corners and relatedbuild-up and undesirable back pressure at the output end and permittingstacking of the screw filters in series; screws removable in halfflights from the screw shaft; and outer helical surfaces of said screwsdefined by bristles of metal, such as stainless steel or brass. Inpreferred embodiments of the disc press subcombination of the inventionare featured mounting the pair of frustoconcal discs for rotation aboutaxes in the same hori zontal plane, inlet pressure sensing means forvarying disc rotation rate, labyrinth disc seals, and a doctor memberincorporating a wash water chamber and a knot-removing auger. Alsofeatured, in combination with a disc press, is a shredder comprising amultiplicity of teeth moved to engage the pressed product coming fromthe disc press.

Other objects, features, and advantages will appear from the followingdescription of a preferred embodiment of the invention, taken togetherwith the attached drawings thereof, in which:

FIG. 1 is a side elevation, to a large extent broken away in verticalsection, thereof;

FIG. 2 is a section at 22 of FIG. 1;

FIG. 3 is a section, broken away, at 3-3 of FIG. 1;

FIG. 4 is a partial end elevation;

FIG. 5 is a broken away sectional view of a portion of the filter screw,taken on a plane through the axis thereof;

FIG. 6 is a somewhat diagrammatic view of screw filter showing the headadjustment standpipe in two positions; and

FIG. 7 shows two screw filters in series.

Referring now more particularly to the drawings, there is shown-in FIG.-1 liquid removing apparatus adapted to, for example, bring solidscontent of slurries ofpfood fiber in water from 4% or less to 40% ormore.

The liquid removing apparatus includes a screw filter, indicatedgenerally at 10, secured at its outlet end to a disc press, indicatedgenerally at 12.

The screw filter 10 has a stainless steel screw .14 mounted for rotationon shaft 16 carried. by bearings 18 and 20..Bearing 18 iswater-lubricated, with a Micarta bushing. Bearing 20 is provided withroller bearings. Screw 14 is in two parts 14a and 14b,,each of whichsurrounds the shaft 16 for and may easily be disassembled for cleaningor maintenance. Secured all along the helical edge of the main portion22 of screw 14 are bristles 24 of stainless steel, which define .ahelical brush. The outer surface of this brush is ground for.dimensional precision; the length-of the bristles before grinding isindicated (FIG. 5) in dotted lines. Also in two semicylindrical portionsare perforated stainlesssteel plate filtering screen 26 and stainlesssteel casing 28, both of which like the screw are bisected essentiallyby a plane in which lies the axis of both. (A gasket, not shown, isprovided between the two casing halves.) The lower half of casing 28 issecured at its lower end to base 30, a 45 elbow with stainless steelstock contacting surfaces, and at its top to stainless steel member32,.the end of which is also symmetrical about an axis at 45 to the axisof shaft 16, making removal of the top half simple for maintenance orcleaning. Mounted on shaft 16 for selective longitudinal positioningthereon is lump breaker 34, which may be moved up or down as it isdesired respectively to decrease or increase operating pressure withinscreen 26. The shaft 16 is driven by motor 36 through belt 38. Effectivehead may also be modified by using standpipe 39, as shown in FIG. 6. Useof more thanone of the screw filters 10 is shown in FIG. 7; such use isfacilitated by having the inlet and outlet axes of each filter divergeoppositely from the screw axis.

Slurry thickened in the screw filter 10 emergestherefrom directly intoinlet zone 40 of housing 42 (cast from Meehanite CC acid-resisting iron)of disc press 12. Beneath zone 40 are portions of two discs44 withfrustoconical pressing surfaces 46. Each surface 46 includes amultiplicity of holes 48 which extend throughthe discs. The holes 48communicate with liquid-collecting concentric grooves 50 and radialgrooves 52 (FIG. .1, shown n the upper right-hand quadrant, wherethe'screen is broken away). The axes of rotation 54 and 56 of discs 44are in the same horizontal plane, which among other things gives theadvantage of simplifying. bearing requirements (FIG. 2). The discs arerotated thereabout by motor 58, which drives them through gears 60, theouter peripheriesof the discs constituting mating bevel gearing. Thediscs are'held on shafts 59 by locking plates61. Each pressing surface46 is covered by stainless steel screen 62 (FIG. 1), which is in twosymmetrical pieces. The screens are fabricated with the sameconicalangle as the disc surfaces 46, the latter being machined (in a finalstep for accuracy) on discs 44 (which areeach cast in one piece withradial ribs 64 from Meehanite CC acid-resisting iron), so that accuratemating for field assembly is assured. Housing 42 (which includes anupper and a lower portion) includes therearound two sets 66 of labyrinthsealing grooves, each set cooperating with labyrinth sealing projectionson one of the discs, to make practical use of the disc pressWith'tninner slurries. Integral with housing 42 is dependent doctor 70,the sides of which are spaced closely to the screens 62 of the rotatingdiscs. Water lubrication is through holes 71 running at an angle fromthe wash chamber 72 and opening through the doctor 70 at its surfacesengaged by the screened discs. The doctor 70 includes three dependingstruts which define with the screens 62, a wash chamber 72 and a knotremoval chamber 74. Knots carried by screens 62 into the chamber 74 arerubbed from said screens (FIG. 3) by auger 76 and outwardly moved by thesame (rotated by motor 78) for ejection through opening 80 (from whichthey may be reintroduced, to be broken up, into the stock to be fed tothe screw filter). Wash water introduced through pipe 82 to wash chamber72 permits washing out directly through screens 62 without stoppingoperation or making disassembly. The bottom half of housing 42 carrieswashout drain 84. Fluid squeezed through screens 62 emerges throughholes 48. Rate of rotation of discs 44 is varied by pressure sensor 85,mounted in inlet zone 40, which varies the speed of motor 58 to maintaina constant pressure in zone 40. The sensor 85 may for example be of theConsotrol M/SZA type sold by The Foxboro Company, Foxboro, Mass.

Exit zone 86 is above the area of greatest solids compression (which isalong a horizontal plane through the horizontal centerline of thesqueezing zone between the discs), so that the outcoming material isallowed to expand transversely as it is leaving. Also, because the zone86 is thus positioned, the .outcoming product is free to expandupwardly, which it does, facilitating and cooperating with the action ofshredder 90, which acts on the emerging bulk to break it into discretesmall pieces well adapted for pneumatic transmission therefrom.

Shredder 90, which provides uniformity of discharge as well aspellet-sized output, provides 51,000 shredding edges 92 acting againstthe output solids per minute. Although diagrammatically shown in thedrawings, these teeth with shredding edges 92 are in a preferredembodiment set at many different pitches, and are carried by amultiplicity of strands of chains running on sprockets 94 and driven bymotor 96 through belt 98. Shredder 90 drives shredded cake away fromdiscpress 12 at about 430 feet per minute. The chains bearing toothededges 92 run on rolling bearings, and the entire shredder is pivotallymounted on the disc press, both for ease of access and as a safetymeasure in the event of drive failure to permit cake to emerge freely.

The operation of the apparatus will be apparent in what has already beensaid. When the discharge from screw filter, to disc press 12 is about 8%or more, the portion 32 is removed, so that exit may be through the zonetherebeneath as well as through the zone otherwise available.

Other embodiments within the following claims will occur to thoseskilled in the art.

What is claimed is:

1. Liquid removing apparatus comprising a screw filter with an outputzone,

a disc press having an input zone, horizontal axes of rotation, and e anoutput zone above said axes,

a pressure sensor in said input zone operative to vary the rate ofrotation of the discs of the disc press to tend to keep constant thepressure in said input zone, and

a shredder above the press output zone, said shredder comprising amultiplicity of teeth rapidly and successively engaging the output ofsaid press output zone.

2. The apparatus of claim 1 in which said disc press includes a centraldoctor downwardly dependent between said discs and in close proximitythereto, said doctor comprising a doctor surface and a pair ofdownwardly extending cavities defining with said discs and the screensthereover a wash chamber and a knot remover.

3. The apparatus of claim '2 in which said central doctor is an integralportion of a housing, said housing cooperating with each of said discsaround the outer opposed peripheries thereof in labyrinth seals.

4.,The apparatus of claim 3 in which said filter includes a screw and aforaminous cylinder engaged by the outer helical surface of said screw,said outer helical surface being defined by a multiplicity of metalbristles, and in which said filter includes also inlet and outletmembers, the axes of symmetry of said inlet and outlet members divergingin opposite directions from the axis of said screw.

5. A disc press comprising a pair of discs mounted for rotation about apair of axes, said axes intersecting intermediate of said discs in anangle, said discs including facing frustoconical surfaces definingtherebetween a pressing zone varying in thickness from a widestthickness in connection with an input zone to a narrowest thickness inconnection with an output zone, and a doctor extending between saidfrustoconical surfaces radially thereof outside said pressing zone, andwith transverse surfaces conforming closely with said frustoconicalsurfaces, said doctor including a radially extending opening in contactthrough said transverse surfaces with said discs, and a washing fluidsupply line to said opening.

6. A disc press comprising a pair of screened discs mounted for rotationabout a pair of axes, said axes intersecting intermediate of said discsin an angle, said discs including facing frustoconical surfaces definingtherebetween a pressing zone varying in thickness from a widestthickness in connection with an input zone to a narrowest thickness inconnection with an output zone, a doctor extending between saidfrustoconical surfaces radially thereof outside said pressing zone, andwith transverse surfaces conforming closely with said frustoconicalsurfaces, said doctor including a radially extending opening in contactthrough said transverse surfaces with said screened discs, and a cleanermounted in said opening, said cleaner being movable in contact with saidscreened discs to remove knots therefrom and into said chamber.

7. Liquid removing apparatus comprising a disc press with a pair ofdiscs mounted for rotation about a pair of axes intersectingintermediate of said discs in an angle, said discs including facingfrustoconical surfaces defining therebetween a pressing zone varying inthickness from a widest thickness in connectionwith an input zone to anarrowest thickness in connection with an output zone, and a shreddermountedat said output zone in spaced relation from said narrowestthickness, said shredder including a multiplicity of shredding surfacesmoving rapidly at an angle to the direction of output in said outputzone to discharge product in shreds at a different angle.

8. A disc press comprising a pair of discs mounted for rotation about apair of axes, said axes intersecting intermediate of said discs in anangle, said discs including facing frustoconical surfaces definingtherebetween a pressing zone varying in thickness from a widestthicknessin connection with an input zone to a narrowest thickness in connectionwith an output zone, a housing cooperating with each of said discsaround the outer opposed peripheries thereof in labyrinth seals, and adoctor extending between said frustoconical surfaces radially thereofoutside said pressing zone, and with transverse surfaces conformingclosely with said frustoconical surfaces, said doctor including a pairof radially extending openings each in contact through said transversesurfaces with said discs, said doctor being integral with said housing,one of said chambers being provided for access to washing fluid and theother of said chambers having mounted therein a cleaner for movement incontact with said discs to transfer knots therefrom into thelast-mentioned chamber.

9. The press of claim '8 in which said cleaner is an auger mounted forrotation about a radial axis in contact with said screened discs totransfer knots therefrom and i move said knots radially from thechamber.

10. A disc press comprising a pair of screened discs mounted forrotation about a pair of horizontal axes, said axes intersectingintermediate of said discs in an angle, said discs including facingfrustoconical surfaces defining therebetween a pressing zone varying inthickness from a Widest thickness in connection with an input zone to anarrowest thickness in connection with an output zone, a housing withperipheries cooperating with facing peripheries of said discs to providelabyrinth seals therearound, said housing including an integraldownwardly and radially extending doctor with transverse surfacesconforming closely with said frustoconical surfaces, said doctor including a pair of radially extending openings each in contact throughsaid transverse surfaces with said screened discs, one of said chambersbeing provided for access to washing fluid and the other having mountedtherein for rotation about a generally radial axis an auger contactingsaid screened discs, a variable speed motor for driving said discsjointly at selectively variable speeds, and a pressure sensor in saidinput zone, said pressure sensor signalling said motor to increase thespeed thereof upon a rise in pressure and decrease the speed thereofupon a decrease in pressure to minimize pressure variation in said inputzone.

11. Liquid removing apparatus comprising a screw filter with an outputzone,

a disc press comprising a pair of discs mounted for rotation about apair of axes intersecting intermediate of said discs in an angle, saiddiscs including facing frustoconical surfaces defining therebetween apressing zone varying in thickness from a widest thickness in connectionwith an input zone to a narrowest thickness in connection with an outputzone, said input zone being in closed communication with said outputzone of said screw filter whereby the fluid pressure at said input zonemay be controlled, and

a pressure sensor responsive to rate of output through said output zoneof said screw filter to decrease the speed of rotation of said discsupon a drop of said rate, whereby substantial reduction of pressure insaid input zone is prevented.

References Cited UNITED STATES PATENTS 772,230 10/1904 Farner 100-1451,630,430 5/1927 Holter 100-145 2,146,158 2/1939 Scherer 100116 X2,327,448 '8/ 1943 Olive 10047 2,793,583 5/1957 Messing 100121 3,062,12911/1962 Wandel 100-117 X 3,188,942 6/1965 Wandel 100117 X 3,218,96311/1965 Ginaven 100121 ROBERT W. JENKINS, Primary Examiner.

1. LIQUID REMOVING APPARATUS COMPRISING A SCREW FILTER WITH AN OUTPUTZONE, A DISC PRESS HAVING AN INPUT ZONE, HORIZONTAL AXIS OF ROTATION,AND AN OUTPUT ZONE ABOVE SAID AXES, A PRESSURE SENSOR IN SAID INPUT ZONEOPERATIVE TO VARY THE RATE OF ROTATION OF THE DISCS OF THE DISC PRESS TOTEND TO KEEP CONSTANT THE PRESSURE IN SAID INPUT ZONE, AND